Type[X] not compatible with metaclass of X

The second-to-last line should probably be accepted by mypy, but it currently generates an error because `Type[A]` isn't compatible with the metaclass of `M`:

```py
from typing import Type

class M(type): pass
class A(metaclass=M): pass

a: Type[A] = A
m: M = a    # error, but should be okay
m2: M = A   # no error
```